The present invention related to a truck or the like for conveying ceramic articles, more particularly bricks and tiles, through a kiln, e.g. a tunnel kiln.
It is known that when ceramic articles are conveyed through a kiln, a truck of the aforementioned kind, in order to obtain optimum thermodynamic and fluid-dynamic results, must:
form the hearth of the furnace; PA1 efficiently seal off the heat flow; PA1 efficiently seal off undesired flows of gas (interfering air) entering or leaving the kiln, and greatly reduce any losses of heat (sensible heat) at the kiln outlet. PA1 With regard to its structure, the truck must: bear the load of ceramic articles for which it is designed; PA1 be easy to manipulate during loading or unloading of the ceramic articles to be fired and when they are conveyed through the kiln, and permit a flow of hot fumes below the load so as to obtain desired contact between the fumes and the ceramic articles. PA1 a frame formed on the plate and comprising a number of box-shaped sectional members of refractory material disposed end to end and having a substantially C-shaped cross-section with horizontal arms extending towards the interior of the frame,
Trucks used heretofore for conveying ceramic articles through a tunnel kiln are made of refractory rammed lining and insulating refractories disposed on a metal base frame. Since the trucks are made with particular allowance for their ability to bear a load, they generally have considerable bulk, particularly height, and weight between 1.5 times and twice the weight of the load. This results in well-known, recognized difficulties of manufacturing and manipulating the trucks. Because of their bulk, considerable heat losses occur at the outlet and during their stay outside of the kiln. In addition, continuous damage may be produced by the considerable internal stresses resulting from repeated, intense thermal shocks to which the trucks are exposed when travelling through the furnace, and the considerable temperature differences between their top and bottom walls. As a result, frequent maintenance is required and the average life of the trucks is limited to two or three years. In addition, due to their great bulk, the trucks have such high thermal inertia that they influence the thermodynamic conditions to which the load of ceramic articles is exposed during firing. In order to prevent interfering air entering the kiln, conventional trucks have cross-sectional peripheral edges which are given uniform profiles and are generally made of refractory blocks, which are joined together by an uneconomic, difficult method.
Maintenance of these trucks is expensive because it requires skilled staff and the truck masonry frequently has to be totally taken apart and remade.